Energy harvesting by sweeping voltage-escalated charging of a reconfigurable supercapacitor array

EscaCap is an energy harvester that uses a boost-up charge pump to perform maximum power-transfer tracking (MPTT) while charging a reservoir supercapacitor array (RSA) with a reconfigurable topology. Unlike buck-down type harvesters, the voltage-doubling charge pump of EscaCap enables the sensor nodes to operate under low ambient power conditions. The supercapacitors in the RSA can be dynamically configured for series or parallel topologies by means of a switch array for not only minimizing leakage of the supercapacitors but also improving the charging speed. Furthermore, the RSA of EscaCap is modular and can be easily expanded. Experimental results show that EscaCap can harvest energy efficiently under low and high solar irradiation conditions, achieve shorter charging time, and demonstrate flexibility and robustness.